Structural, Functional, and Molecular Neuroimaging in Depression

Abstract

Depression is a globally prevalent psychiatric disorder which is associated with genetic, environmental, and psychological factors. Structural, functional, molecular neuroimaging approaches, particularly magnetic resonance imaging (MRI) and radionuclide imaging techniques, have been increasingly used to detect neurobiological changes, analyze neurochemical correlates, and parse pathophysiological mechanisms underlying depression. With the use of MRI, structural abnormalities in the prefrontal-subcortical regions involved in the cognitive control of affective state are discovered to be associated with aberrant neural activity. Besides, abnormal functional networks particularly default mode network, as revealed by functional MRI, are likely related to aberrant metabolism and dysfunctional serotonergic system detected by radionuclide imaging. Moreover, radionuclide imaging studies demonstrate that serotonin deficiency in the midbrain may play a critical role in the genesis of depression, and the incongruent reduction of serotonin receptor binding in the prefrontal cortex and midbrain may contribute to the action of suicide. Apart from serotonergic system, dysfunctional striatal dopaminergic system has been identified in depression, and a great dopamine transporter availability may be a state marker of a depressive episode as detected by radionuclide imaging. Future multimodal neuroimaging investigations carried out in multiple sites are essential to clarify the potential associations among these structural, functional, and molecular changes, as well as their implications for behavior and cognitive.